Photographic solvent transfer reproduction process



June 19, 1956 1' JAMES ET AL 2,751,300

PHOTOGRAPHIC SOLVENT TRANSFER REPRODUCTION PROCESS Filed July 15, 1954 EXPOSED AND PARTLY 0E VELOPED ,q x

EMULSION 3 'PYIPAZOL IDONE-ASCORB/C ACID A gX SOL VEN T DEVELOPER Slage] Tbomasli James leonardm'egifils IN VEN TORS' .AT romvs PHOTOGRAPHIC SOLVENT TRANSFER REPRODUCTIUN PROCESS Thomas H. James and Leonard W. Tregillus, Rochester,

N. Y., assignors to Eastman Kodak Company, Rochester, N. Y., a corporation of New Jersey Application July 15, 1954, Serial No. 443,536 8 Claims. (CI. 95-88) This invention relates to a photographic solvent transfer reproduction process of the type in which an exposed silver halide emulsion is developed in the presence of a silver halide solvent such as sodium thiosulfate in contact with a receiving sheet with the result that a silver image is developed in the emulsion layer and thereafter the residual silver halide is dissolved by the silver solvent and transferred imagewise by diffusion to a receiving sheet where it is transformed to metallic silver or other silver compound of high optical density. Processes of this type have been described at some length in the patent and periodical literature.

One characteristic of such processes is that they should, for best results, employ a developer composition containing, in addition to a silver halide solvent, a high-energy silver halide developing agent in order that negative development will be essentially complete before the unexposed silver halide begins to dissolve in the silver halide solvent. Yet the fogging action which is typical of highenergy silver halide developers must be kept to a minimum. In these processes, common high-energy developers must be used at relatively high pH values and tend not only to give excessive fog but cause excessive stain when transferred to the receiving sheet at the high pH required for the process. Other developing agents giving a low level of stain are of too low activity to be of use.

We have discovered a combination of silver halide developing agents for use in such processes which have no propensity to the formation of stain in the process and while they are inherently very low-energy developing agents per se, when they are used in combination a synergistic effect appears and a very high-energy developer system results. Since the developing agents themselves have little or no propensity to the formation of stain, the process yields reproductions of very high quality.

The development system we employ in the solvent transfer processes for development in the presence of silver halide solvents is a combination of a 3-pyrazolidone silver halide developing agent and an ascorbic acid developing agent such as l-ascorbic acid and d-iso-ascorbic acid. The 3-pyrazolidone silver halide developing agents and ascorbic acids alone are very low-energy silver halide developing agents, yet in combination give the desired high-energy developing system.

The 3-pyrazolidone silver halide developing agents employed in combination with ascorbic acid have the general structure in which the R groups each represent various substituents such as hydrogen, alkyl or aryl groups, for example R1 can be hydrogen or a group such as alkyl preferably con taining from 1 to 4 carbon atoms, or an aryl group of the benzene or naphthalene series substituted or not, and R2, R3, R4 and R5 can be hydrogen atoms or alkyl as above or aryl such as phenyl.

The following compounds are representative of 3- pyrazolidone silver halide developing agents which are useful in the developer compositions of the invention:

. l-phenyl-S-pyrazolidone 1-p-tolyl-3-pyrazolidone 5-phenyl-3-pyrazolidone 5-methyl-3-pyrazolidone 1-p-chlorophenyl-3-pyrazolidone 1-pheny1-5-phenyl-3-pyrazolidone 1-m-tolyl-3-pyrazolidone 1-phenyl-5-methyl3-pyrazolidone 1-p-to1y1-5-phenyl-3-pyrazolidone 1-m-tolyl-3-pyrazolidone 1-p-methoxyphenyl-3-pyrazolidone 1-acetamidophenyl-3pyrazolidone 1-phenyl-2-acety1-4,4-dimethyl-3-pyrazolidone 1-phenyl-4,4-dimethyl-3pyrazolidone 1-m-aminophenyl-4-methyl-4-propyl-3pyrazolidone 1-o-chlorophenyl-4-methyl-4-ethyl-3pyrazolidone 1-m-acetamidophenyl-4,4-diethyl-3-pyrazolidone 1-(p-fi-hydroxyethylphenyl)-4,4-dimethyl 3 pyrazolidone 1-p hydroxyphenyl-4,4-dimethyl-3pyrazolidone 1-p-methoxyphenyl-4,4-diethyl-3-pyrazolidone 1-p-tolyl-4,4-dirnethyl-3-pyrazo1idone 1-(7-hydroxy-2-naphthyl)-4-methyl 4 n ropyl-3- pyrazolidone 1-p-diphenyl-4,4-dimethyl-3-pyrazolidone 1-(p-B-hydroxyethylphenyl)-3-pyrazolidone 1-o-tolyl-3-pyrazolidone 1-o-tolyl-4,4-dimethyl-3-pyrazo1idone 1-phenyl-4-methyl-3-pyrazolidone The 4,4-dialky1-3-pyrazolidone compounds 13 to 23 and 26 above are particularly efiicacious for use in the developer compositions of our invention inasmuch as they are more active developing agents than are compounds 1 to 12 which contain a single substituent or only hydrogen atoms in the 4-position of the pyrazolidone nucleus. The 4,4-dialkyl-3-pyrazolidone compounds are described and claimed in the Allen et a1. U. S. patent application Serial No. 372,148 filed August 3, 1953. The w-hydroxyalkyl-3-pyrazolidones, for example, compounds 18 and 24 above, are also useful. Compounds 18 and 24 are described in the Reynolds et a1. U. S. patent application Serial No. 372,167, filed August 3, 1953, and Allen et a1. U. S. patent application Serial No. 372,148, filed August 3, 1953.

A particularly efiicacious group of 3-pyrazolidone developing agents for use in combination with ascorbic acid and a silver halide solvent in the developer compositions of the invention are compounds Nos. 1, 2, 14, 18, 21, 24 and 27 of the above tabulation.

Our invention will now be described with particular reference to the accompanying drawings illustrating means for carrying out our invention.

Example 1 Receiving sheets used in this and the following examples were prepared by depositing upon a baryta-coated paper Accordingly, the resulting receiving sheet carries on its surface a material which will react with the transferred silver ions in the presence of the silver halide solvent to form an image on the receiving sheet, in this case, of silver sulfide, upon which, by physical development, additional metallic silver is deposited to produce an image having appreciable optical density.

The undesirable staining properties of a typical highcnergy silver halide developer composition was demon strated by exposing a negative-speed bromoiodide emulsion layer of conventional hardness to a line, halftone or continuous-tone subject and developing the exposed emulsion layer in the following composition:

Water ml 1000 Sodium sulfite grams 80 Hydroquinone do 35 Sodium thiosulfate do Sodium hydroxide do 28.5 Potassium bromide do 2.5 0.5% benzotriazole ml 25.0

by simultaneously immersing both the exposed element and the receiving sheet in the developer composition for six seconds and immediately thereafter pressing the two elements together face to face inside a fold of paper and drawing them between a pair of pressure rollers under siight tension. After one minute the receiving sheet was separated from the negative, at which time the processing was complete. The process will be understood more fully from consideration of the accompanying drawings wherein stage 1 shows the two sheets at the moment of contact.

The negative sheet has the support 10 carrying the emulsion layer 11 containing the exposed areas 12 and 13, which have been developed in the previous 6-seeond immersion in the developer. The receiving sheet consists of a support and a layer 21 thereon containing the sulfide precipitation nuclei. At this stage, the development of the exposed areas 12 and 13 of the negative is substantially complete, and the silver halide solvent of the developer solution is about to dissolve the residual silver halide in the negative in order that it may diffuse to the areas 22 and 23 of the receiving sheet. In stage 2 of the drawings is shown the appearance of the receiving sheet following the transfer and physical development of the residual silver halide wherein areas 24 and 25 represent the deposit of silver sulfide and metallic silver. In order to accelerate the growth of stain on storage of the print, the print was incubated for 12 hours at 80 C. and 90% relative humidity. These conditions approximate one years storage under normal room conditions.

When the resulting image on the receiving sheet was thus incubated, a stain density (measured through a blue filter) of 0.16 was present in the highlights of the print. When the process was repeated with a standard silver chloride emulsion, a stain density of 0.12 was obtained.

Example 2 A negative film carrying a bromoiodide emulsion was processed as in the above example except that the following developer composition was employed:

Water ml 100 Sodium sulfite grams 8 d-Iso-aseorbic acid do 5 Sodium thiosulfate do 3 Sodium hydroxide do 2.5 Potassium bromide do 0.2 l-phenyl-B-pyrazolidone do 0.25 0.5% enzotriazole ml 5.0

After incubation of the resulting print under the above conditions, it was found that the stain density was only 0.05 showing a marked improvement in stain level over the use of the conventional hydroquinone developer of Example 1.

Example 3 The procedure of Example 1 was carried out with the I 4 bromoiodide negative film and the following developer composition:

Water ml Sodium sulfite grams 8 d-lso-ascorbic acid do 5 Sodium thiosulfate do 5 Sodium hydroxide do 2.65 l-phenyl-3-pyrazolidone do 1.0 0.5% benzotriazole ml 5.0

The incubated print obtained thereby had a stain density of 0.04.

Example 4 The procedure of Example 1 was carried out with a silver chloride negative paper and a developer solution having the following composition:

Water ml 100 Sodium sulfite grams 8 d-lso-ascorbic acid do 5 Sodium thiosulfate do 3 Sodium hydroxide do 3 Potassium bromide do 0.5 l-phenyl-3-pyrazolidone do 0.25 0.5% benzotriazole ml 5.0

The stain density on the print obtained after incubation was 0.02.

Example 5 An emulsion coating on paper was prepared which contained 0.287 gram of silver chloride, 0.74 gram of gelatin, 0.20 gram of di-isoascorbic acid, and 0.01 gram of lphenyl-3-pyrazolidone per square foot. Using this material as the negative, it and the receiving sheet above were immersed in an activator solution consisting of:

Water ml 200 Sodium thiosulfate grams 8 Sodium hydroxide do 6 Sodium sulfate do 10 After completing processing as in Example 1, the incubated print had a stain density of 009.

Example 6 A silver chloride-sensitized negative paper and the same receiving sheet were utilized as in Example 1 with the following developer composition:

Water ml 100 Sodium sulfite "grams..- 8 d-Iso-aseorbic acid do 5 Sodium thiosulfate do 3 Sodium hydroxide do 3 Potassium bromide do 0.3 4,4-dimethyl-l-phenyl-3-pyrazolidone -do 0.6 0.5% benzotriazole ml 5.0

The stain density on the resulting incubated print was 0.04.

Example 7 The procedure of Example 6 was carried out except utilizing the following developer composition:

incubation. An identical result was obtained in the same procedure except employing a bromoiodide negative film.

Example 8 The bromoiodide negative film and receiving sheet were processed as above with the following developer composition:

Water ml 100 Sodium sulfite grams 8 d-Iso-ascorbic acid do 5 Sodium thiosulfate ..do 5 Sodium hydroxide do 3 Potassium bromide ..do 0.5 4,4-dimethyl-l-p-tolyl-3-pyrazolidone do 1.0 0.5% benzotriazole ml 5.0

The stain density of the resulting incubated print was 0.02.

Example 9 The procedure of Example 1 was carried out with a silver chloride paper and the following developer composition:

Water ml.... 100 Sodium sulfite ..grams 8 d-Iso-ascorbic acid do.. 5 Sodium thiosulfate do 3 Sodium hydroxide do 3 Potassium bromide do 0.5 l (4'-/ -hydroxyethylphenyl)-3- pyrazolidone do 0.5 0.5% benzotriazole ..ml 5.0

The stain density of the print obtained after incubation was 0.03.

Example 10 The following developer compositions were provided:

A. d-Iso-ascorbic acid developer:

Samples of the bromoiodide negative film were exposed to a subject and processed with developers A and B in the following manner. A small amount of the highly viscous developer was placed near one end of the negative film, and the receiving sheet was placed on top of the negative film and the pile of developer. The developer was spread between the film and sheet at a thickness of 0.003 inch by passing the sandwich between accurately adjusted rollers. After a transfer period of 2 minutes, the film and sheet were separated and each receiving sheet contained an image as well as a layer of developer. After incubation, the stain density for the print resulting from development with developer A of the invention was 0.02 and for the print obtained with the hydroquinone developer B a stain density of 0.29.

Additional examples (11 to 16) illustrating our invention are provided by the table following. For these examples, the procedure of Example 1 was carried out using samples of a silver chloride-sensitized negative paper and the same receiving sheet in each case with the respective developers of compositions shown in the table. In the latter portion of the table, Sample A and Sample B indicate that duplicate tests were conducted with the respective developers. Examples 13 and 14 demonstrate the use of 1-phenyl-3-pyrazolidone and ascorbic acid alone as developing agents. 1-phenyl-3-pyrazolidone itself is a very weak developing agent yet when employed in the process of the example gave a useful image with stain density of 0.08 to 0.06 after incubation of the prints. The minimum density values of 0.32, 0.33 and 0.35 of Example 14 represents silver density and do not represent stain on the incubated samples. This silver density results from the fact that as mentioned, ascorbic acid is such a weak developing agent in the absence of the 3-pyrazolidone compounds that the negative image is incompletely developed in the process and therefore appreciable silver halide transfers to the receiving sheet at the same time as the silver halide from the unexposed area of the sheet is transferring.

Examples 15 and 16 compare the use of 1-phenyl-3- pyrazolidone and hydroquinone respectively, in an ascorbic acid developer container hypo as the silver halide solvent. It is apparent from the results that the 1-phenyl- 3-pyrazolidone-ascorbic acid system is more effective in reducing stain. Example 11 duplicates, for comparison, the developer of Example 1, and Example 15 duplicates Example 4. Examples l2, 13, 14 and 16 were prepared to resemble Example 15 in all respects (including pH) except for the developing agents. In Example 12 there is used hydroquinone as the developing agent, and the high stain densities of 0.12 and 0.18 were obtained upon incubation of the prints.

Developer Feature Ex. 11 Ex. 12 Ex. 13 Ex. 14 Ex. 15 16 Ex.

Water, ml 200 200 200 200 200 200 Sodium sulfite, dess., gms. 16 16 16 16 16 16 Ascorbic acid, gms 10 10 10 Hydroquinone, gms 7 7 7 Hypo, gins 3 6 6 6 6 6 Sodium hydroxide, gms 5. 7 5. 7 1. 5 6 6 11 Potassium bromide, gms 0. 5 1. 0 1. 0 1. 0 1.0 1. 0 PD2,(1-phenyl-3-pyrazolidone) gms 0. 5 0. 5

.5% Benzotriazole, ml 5 10 10 10 10 10 Sample A, orig;

D-min 0. 065 0. 06 0.32 0. 07 0. 06

-min 0. 06 0. 1O 0. 05 0. 335 0. 075 0. 065

D-min O. 16 O. 18 0. 06 0. 35 0. 060 0. 10

As noted in Example 5, the 3-pyrazolidone developing agent and the ascorbic acid developing agent may be contained in a colloid layer of the light-sensitive negative element and the alkaline activating bath then contains principally the silver halide solvent. If desired, either one of the developing agents may be incorporated into the emulsion while the other is contained in the alkaline developer with the silver halide solvent.

If desired, the mentioned procedures may be employed in conjunction with a variety of receiving layers, sheets or elements having on their surfaces a material which will precipitate silver from solution in the presence of the silver halide solvent and other ingredients of the development system to form an image of appreciable optical density on the receiving sheet such as silver or silver sulfide. Accordingly, the receiving sheet may, for example, carry on its surface one or more of the following silver precipitants:

Sodium sulfide, selenide or telluride Zinc sulfide Aminoguanidine sulfate Aminoguanidine carbonate Arsenous oxide Sodium stannite Thiourea and its derivatives 7 Substituted hydrazines Organic sulfiding agents e. g. mercaptans Xanthates Finely divided silver Stannous chloride Finely divided sulfur Silver sulfide Finely divided gold These materials vary somewhat in the manner in which they effect precipitation of silver from solution. The finely divided metallic and non-metallic silver precipitants such as colloidal silver, gold and silver sulfide provide nucleatlng centers which initiate physical development of the silver halide transferred to receiving sheet. A second group of these silver precipitants, including the guanidine derivatives, arsenous oxide, stannite, hydrazines and stannous chloride have reducing properties and react with dissolved silver transferring to the receiving sheet to form colloidal particles on which physical development can take place. The third group of silver precipitants including the alkali metal sulfides, selenides and tellurides, Zinc sulfide, thiourea and its derivatives, mercaptans, Xanthatcs and colloidal sulfur, react with dissolved silver transferring to the receiving layer to form thereon an insolubl precipitate such as silver sulfide on which physical development can take place. It will be noted that silver precipitants of the latter class such as zinc sulfide, contain a reactive sulfur atom and can be used on the receiving element in minor quantities to catalyze the reduction of the silver halide transferring to the sheet, to precipitate metallic silver, or in increased quantities to react with the silver halide in the presence of the silver halide solvent to precipitate a silver sulfide image on the receiving element.

Silver halide solvents useful in the developer compositions are, for example, ammonium hydroxide, ammonium chloride, ammonium sulfate, ammonium nitrate, sodium thicsulfate, sodium sulfite, a hall metal thiocyanates, sodium bisullite, potassium metabisulfite.

The amount of silver halide solvent used in the developer compositions will naturally depend upon a number of factors. Since it is desired that thetransfer of silver halide to the receiving sheet take place in a reasonably short period of time, quantities of the order of from about 15 to 75 grams per liter of developer give good results. The more active silver halide solvents, such as sodium tbiosulfate and sodium sullite, operate well in this range and less active silver halide solvents in similar proportions will be found to decrease the rate of transfer of silver halide. Quantities of active solvent such as sodium thiosulfate in concentrations of as little as 3 to 5 grams per liter are useful but give less desirable results. Also with certain emulsions, such as silver chloride emulsions, less a "ivc silver halide solvents, such as ammonium hydroxide, give better results than with bromoiodide emulsions. Also with the reduced concentrations of the weaker silver halide solvents, there is a tendency to obtain some lateral diffusion of the dissolved silver halide.

As mentioned, it is desirable to employ a high-energy developer system in the process. Therefore, sufficient ascorr-ic acid is used in the developer compositions or in the emulsion to obtain the required development rate. Ratios of ascorbic acid to the S-pyrazolidone compound of the order of from 3:1 to 20:1 or greater provide useful results but it will be apparent that factors of economy are to be considered when using the higher concentrations of ascorbic acid and at the lower levels the development rate is decreased.

With any solvent transfer system in which a single developing solution is employed, there is required a definite order of reaction rates, wherein the development rate must be fastest, the silver halide solvent action the next fastest, and the negative fog formation the slowest. The time intervals given in the examples of this invention represent arbitrary choices to which the developer compositions have been balanced. The limits Within which the developers of the invention will produce useful transfer images, with the exception of Example 10 which is controlled by the thickness of the developer film and the developer composition, are, at 74 F., 2 seconds to 20 seconds for the immersion in the developer, and at least 15 seconds for the transfer period. For transfer periods greater than about 5 minutes it is necessary to make special choices of colloids for the vehicles for the silver halide grains on the negative sheet and the precipitation nuclei and whitening agents, such as baryta, on the receiving sheet, in order to prevent sticking.

The degree of alkalinity of the developer solutions containing a 3-pyrazolidone and ascorbic acid as the developing agents for the solvent transfer process has been found to vary with the type of negative emulsion employed. In general, the best results are obtained between a pH of 12.2 and 13.2 for the negative speed bromo-iodide emulsion, and between 12.8 and 13.2 for the positive speed chloride emulsion, giving an over-all range of about 12.2 to 13.2. The pH measurements were made with a glass electrode and corrected for the sodium ion concentration.

The effect of the possible use of ascorbic acid only in the receiving sheet will be apparent when it is considered that the ascorbic acid must then be dissolved by the developer solution and then migrate to the silver halide emulsion layer'before the desired high energy development can take place. This is particularly true when thickened developers are used since the rate of migration of ascorbic acid from the sheet to the emulsion layer is decreased. However, there is no harm in using ascorbic acid in the receiving sheet if it is also present in the developer composition or the emulsion layer or both. Our invention, therefore, does not depend upon the use of ascorbic acid in the receiving sheet.

The developer compositions of the invention containing a S-pyraZolidone silver halide developing agent, ascorbic acid and a silver solvent such as hypo, may contain the latter in a concentration of the order of from about 25 to 50 or more grams per liter of solution. Such developer compositions have interesting applications elsewhere in the photographic art. That is, it has been discovered that such developer compositions can be used tor the development of ordinary silver halide emulsion layers with the result that no subsequent washing of the developed emulsion layer is necessary since the silver halide solvent stabilizes the silver image. A suitable composition for this purpose contains one gram of l-phenyl- 3- pyrazolidone, 50 grams of sodium thiosulfate, 10 grams of d-isoascorbic acid, 2 grams of potassium bromide and 20 grams of sodium carbonate per liter of solution. If desired, 15 grams of potassium iodide may be substituted for the sodium thiosulface in the formula for the same purpose with even better results.

' What we claim is:

1. A photographic reproduction process which comprises exposing a supported silver halide emulsion layer to a subject, developing the exposed emulsion layer in the presence of a 3-pyrazolidone silver halide developing agent and an ascorbic acid developing agent by means of an alkaline developing solution containing a silver halide solvent while said emulsion layer is in intimate contact for a portion of the development period with the surface of a receiving layer containing a silver precipitant, allowing development to proceed until a silver image has been formed in the exposed region of the emulsion layer and until at least a portion of the residual undeveloped silver halide has been dissolved by the silver halide solvent and has been transferred imagewise to the receiving sheet and silver has been precipitated thereon to. form an image of appreciable optical density, then removing the emulsion layer from the receiving layer to obtain said image on the receiving layer.

2. The process of claim 1 wherein the 3-pyrazolidone silver halide developing agent is selected from the class consisting of 1-(p-fi-hydroxyethylphenyl)-3-pyrazolidone, l-(p-fi-hydroxyethylphenyl)-4,4-dimethyl-3-pyrazolidone, l p tolyl 3 pyrazolidone, 1-phenyl-3-pyrazolidone, l phenyl 4,4-dimethyl-3-pyrazolidone, l-p-tolyl-4,4-dimethyl-3-pyrazolidone and l-phenyl-4-methyl-3-pyrazolidone, and the silver halide solvent is in the developer solution.

3. The process of claim 1 wherein the silver halide solvent present in the developer solution is selected from the class consisting of alkali metal and ammonium thiosulfates.

4. The process of claim 1 wherein the receiving layer carries a silver precipitant containing a sulfur atom reactive with silver halide in the presence of the silver halide solvent of the developer to form silver sulfide.

5. The process of claim 1 wherein the receiving layer carries a substance which initiates physical development of the silver halide transferring to the receiving sheet.

6. The process of claim 1 wherein the exposed emulsion layer contains a 3-pyrazolidone silver halide developing agent and an ascorbic acid developing agent, and the alkaline developer solution contains a silver halide solvent.

7. A photographic developer composition containing an alkaline material, ascorbic acid, a 3-pyrazolidone silver halide developing agent and at least about 15 grams per liter of a member of the class consisting of alkali metal thiosulfates, ammonium thiosulfate, sodium sulfite, sodium bisulfite, and potassium metabisulfite.

3. The process of claim 1 wherein the 3-pyrazolidone developing agent is present in the developing solution.

OTHER REFERENCES Varden PSA Journal, vol. 13, Sept. 1947, PP- 551-554. 

1. A PHOTOGRAPHIC REPRODUCTION PROCESS WHICH COMPRISES EXPOSING A SUPPORTED SILVER HALIDE EMULSION LAYER TO A SUBJECT, DEVELOPING THE EXPOSED EMULSION LAYER IN THE PRESENCE OF A 3-PYRAZOLIDONE SILVER HALIDE DEVELOPING AGENT AND AN ASCORBIC ACID DEVELOPING AGENT BY MEANS OF AN ALKALINE DEVELOPING SOLUTION CONTAINING A SILVER HALIDE SOLVENT WHILE SAID EMULSION LAYER IS IN INTIMATE CONTACT FOR A PORTION OF THE DEVELOPMENT PERIOD WITH THE SURFACE OF A RECEIVING LAYER CONTAINING A SILVER PRECIPITANT, ALLOWING DEVELOPMENT TO PROCEED UNTIL A SILVER 